oe7drt-website

dominic

oe7drt-website

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Systemd Unit files

A nice and informative article about unit files.

https://www.digitalocean.com/community/tutorials/understanding-systemd-units-and-unit-files

Unlock locked user accounts

If your user account is locked, wait 15 minutes (usually) and you can try again.

If you need to unlock your account immediately: run this command (if you have another user that can login on the box):

$ sudo faillock --user dominic --reset

Calling faillock without arguments show an overview.

Predictable network interfaces

Get back the "old" interface names like eth0 or wlan0 with {{< man systemd.link 5 >}}.

Ethernet

This makes my ethernet interface be called eth0 again.

Create /usr/lib/systemd/network/80-ether.link with this content:

[Match]
Type=ether

[Link]
NamePolicy=keep kernel

Reboot.

Wireless

This makes my wireless interface be called wlan0 again.

Create /usr/lib/systemd/network/80-wlan.link with this content:

[Match]
Type=wlan

[Link]
NamePolicy=keep kernel

Reboot.

Setup WiFi networks

Using iwctl

$ iwctl device list
$ iwctl station wlan0 scan
$ iwctl station wlan0 get-networks
$ iwctl station wlan0 connect {ssid}

Using nmcli (NetworkManager)

$ nmcli device wifi list
$ nmcli device wifi rescan
$ nmcli device wifi connect {ssid} --ask
$ nmcli device wifi show-password

Last command shows the connected SSID and a QR-code within the terminal.

Using NetworkManager

We create some files in /etc/NetworkManager/conf.d:

Using `iwd` as the WiFi backend

wifi_backend.conf:

[device]
wifi.backend=iwd

Using `dhcpcd` as DHCP client

dhcp-client.conf:

[main]
dhcp=dhcpcd

Blocking IPs from a list with ipset

Using ipset should increase performance on the box, also using the raw table should not create useless states as for what I understand from the source article on serverfault.com.

$ sudo ipset -N badips iphash
$ while read ip; do sudo ipset -A badips "$ip"; done < blocked.txt
$ sudo iptables -t raw -I PREROUTING -m set --match-set badips src,dst -j DROP
$ sudo iptables-save -f /etc/iptables/iptables.rules

Enable iptables in case it is not running yet.

$ sudo systemctl enable --now iptables.service

Also make the ipset configuration persistent:

$ sudo ipset save -file /etc/ipset.conf
$ sudo systemctl enable ipset.service

Reboot to test its persistency.

Do not manage one specific USB dongle

99-unmanaged-devices.conf:

[keyfile]
unmanaged-devices=mac:xx:xx:xx:xx:xx:xx

Prefer local DNS instead of systemd-resolved defaults

https://unix.stackexchange.com/a/442599

CPU frequency scaling

https://wiki.archlinux.org/title/CPU_frequency_scaling

YubiKeys

https://wiki.archlinux.org/title/YubiKey

LunarVim custom key mappings

I know, this is an Arch Linux post but hey, I don't care.

https://github.com/LunarVim/LunarVim/issues/2602

Mounting nfs shares with systemd

https://wiki.archlinux.org/title/NFS#Mount_using_/etc/fstab_with_systemd

Arch Linux ARM installation on a Raspberry Pi 2

The wiki page is for Raspberry Pi 4.

https://archlinuxarm.org/platforms/armv8/broadcom/raspberry-pi-4

Create a 32-bit Wine prefix

I create my wine prefixes usually like this:

$ export WINEPREFIX=/home/dominic/.wine-winlink
$ export WINEARCH=win32
$ wine wineboot

Installing multiple ruby versions

I came to the point to test an older website from me and it was made with Jekyll which I had to install quickly. Problems occured with OpenSSL and I finally managed to install ruby version 2.7.1 and 3.0.0 in my home directory.

$ rvm pkg install openssl
$ rvm install "ruby-3.0.0" --with-openssl-dir=$HOME/.rvm/usr
$ rvm install "ruby-2.7.1" --with-openssl-dir=$HOME/.rvm/usr

Later in the desired directory, I re-installed the gems because with ruby 2.7.1 I got another "Directory not found" error.

I had to do this because I used ruby 2.7.1 on one website.

$ bundle install --force

Bigger font for systemd-boot

Edit /boot/loader/loader.conf:

console-mode 0

Possible settings are:

Value	Description
0	Standard UEFI 80x25 mode
1	80x50 mode, not supported by all devices
2	the first non-standard mode provided by the device firmware, if any
auto	Pick a suitable mode automatically using heuristics
max	Pick the highest-numbered available mode
keep	Keep the mode selected by firmware (the default)

More details can be found in {{< man loader.conf 5 >}}.

Manual sections

Section	Description
1	Section 1 of the manual describes user commands and tools, for example, file manipulation tools, shells, compilers, web browsers, file and image viewers and editors, and so on
2	Section 2 of the manual describes the Linux system calls. A system call is an entry point into the Linux kernel. Usually, system calls are not invoked directly: instead, most system calls have corresponding C library wrapper functions which perform the steps required (e.g., trapping to kernel mode) in order to invoke the system call. Thus, making a system call looks the same as invoking a normal library function.
3	Section 3 of the manual describes all library functions excluding the library functions (system call wrappers) described in Section 2, which implement system calls.
4	Section 4 of the manual describes special files (devices).
5	Section 5 of the manual describes various file formats, as well as the corresponding C structures, if any.
6	Section 6 of the manual describes the games and funny little programs available on the system.
7	Section 7 of the manual provides overviews on various topics, and describes conventions and protocols, character set standards, the standard filesystem layout, and miscellaneous other things.

Encoding videos with ffmpeg

This is not an Arch way of encoding videos, but since I do this on my...

$ ffmpeg -i <input> -c:v libx264 -b:v 1M -maxrate 1M -bufsize 2M -pass 1 -f null /dev/null
$ ffmpeg -i <input> -c:v libx264 -b:v 1M -maxrate 1M -bufsize 2M -pass 2 <output>

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